Local area network having multiple channel wireless access

ABSTRACT

A communication network having at least one access point supports wireless communication among a plurality of wireless roaming devices via a first and a second wireless channel. The access point comprises a first and a second transceiver. The first and second transceivers operate on the first and second wireless channels, respectively. Each of the plurality of wireless roaming devices are capable of communicating on the first and second wireless channel. In one embodiment, the first wireless channel is used to exchange data, while the second channel is used to manage such exchanges as well as access to the first channel. In an alternate embodiment, both channels are used to support communication flow, however the first channel supports a protocol that is more deterministic than that of the second channel. Allocation of ones of the plurality of wireless roaming devices from one channel to the next may occur per direction from the access point. It may also result from decisions made by each of the wireless roaming devices made independent of the access point. For example, a decision may be made based on the data type being transferred or based on the current channel load. Such factors may also be used by the access point for allocation determinations. In addition, allocation may be based on the type of roaming device involved, such as allocating peripherals to a slower channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of co-pending U.S. applicationSer. No. 08/878,357 filed Jun. 27, 1997, which is a continuation-in-partof U.S. application Ser. No. 08/772,895 filed Dec. 24, 1996, abandoned,which is a continuation-in-part of U.S. application Ser. No. 08/696,086filed Aug. 13, 1996, abandoned, which is a continuation of U.S.application Ser. No. 08/238,180 filed May 4, 1994, now issued as U.S.Pat. No. 5,546,397, which is a continuation-in-part of U.S. applicationSer. No. 08/197,392 filed Feb. 16, 1994, abandoned, which is acontinuation-in-part of U.S. application Ser. No. 08/170,121 filed Dec.20, 1993, abandoned.

The U.S. application Ser. No. 08/772,895 filed Dec. 24, 1996, alsoclaims priority to PCT Application Ser. No. PCT/US96/09474, filed onJun. 3, 1996.

All of the aforementioned applications are hereby incorporated herein byreference in their entirety. In addition, U.S. Pat. No. 5,425,051 issuedJun. 13, 1995 to Ronald L. Mahany is also hereby incorporated herein byreference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates generally to access points used inwireless local area networks, and more specifically to an access pointwhich includes multiple wireless adapters.

2. Related Art

Wireless local area networks (WLAN's) use radio frequency transmissionsto communicate between roaming computer devices and access points (orbase stations). The access points are connected to an infrastructurethat electronically connects all of the access points to a host system.The wired infrastructure and the access points make up an informationdistribution network used for the transfer of information and forcommunications.

In a wireless networking environment, various types of devices may needto communicate within a given area. When incompatibilities betweendevice types arise, the wireless infrastructure must accommodate thevarious device types. Accommodating the different device types in asingle infrastructure is generally difficult to accomplish. Further,devices within the wireless networking environment typically communicatediffering types of data, each with its own priority and bandwidthrequirements. Accommodating the various types of data with their relatedpriorities often could not be accomplished by prior devices due tobandwidth limitations, conflicting priorities and incompatible standardswithin the wireless network.

In prior WLANs, a first wireless terminal that desired to communicatewith a base station often could not detect transmissions from a secondwireless terminal currently engaged in ongoing communication with theaccess point. As a result, the wireless terminal often initiatedtransmissions that collided with the ongoing communications. Operationof this type is referred to as a “hidden terminal” situation. To solvethe hidden terminal situation, some prior base stations were configuredwith a second transmitter for delivering a carrier signal on a “busychannel” whenever the base station was engaged in communication on the“data channel.” All terminals were also fitted with a second receiver,tuned to the busy channel, and required to check the busy channel beforeinitiating communication on the data channel. However, the additionalpower required, bandwidth used, hardware needed and associated cost madethe busy channel solution undesirable for most applications.

Some prior WLANs attempted to solve operational difficulties by simplyincreasing the transmission capacity available on the infrastructure.Such expansion temporarily decreased conflicts in operation of theWLANs. However, the infrastructure, which is expensive to install,typically became overloaded quickly resulting in the same or similarproblems.

SUMMARY OF THE INVENTION

The present invention is directed to communication network that supportscommunication within a premises. The communication network comprises anaccess point, a plurality of wireless roaming devices, a first wirelesscommunication channel, and a second wireless communication channel. Theaccess point itself comprises a first processing circuit, a first radiotransceiver coupled to the first processing circuit, and a second radiotransceiver coupled to the first processing circuit. Each of theplurality of wireless roaming devices comprising a second processingcircuit, a third radio transceiver and a radio receiver. Therein, thefirst wireless communication channel that supports communication flowvia the communication network, while the second wireless communicationchannel is used to manage the flow of communication through the firstwireless communication channel. In addition, the first and third radiotransceivers are operable on the first wireless communication channel,while the second radio transceiver and the radio receiver are operableon the second wireless communication channel.

The communication network also supports various other aspects of thepresent invention. For example, the access point may further comprise awired communication interface circuit coupled to the first processingcircuit. Selective participation on the first and second communicationchannels may also provide further benefits. In one embodiment, each ofthe plurality of wireless roaming devices utilizes the radio receiver onthe second wireless communication channel before participating with thethird radio transceiver on the first wireless communication channel. Inanother, each utilizes the radio receiver on the second wirelesscommunication channel to gain access with the third radio transceiver onthe first wireless communication channel. Each may also or alternativelyutilize the second wireless communication channel to identify ongoingcommunication on the first wireless communication channel to, perhaps,provide an indication as to when channel capacity may become available.

Other aspects may be found in an alternate communication network whichalso supports communication within a premises. This communicationnetwork comprises an access point, first and second wirelesscommunication channels and plurality of wireless roaming devices. Thefirst wireless communication channel has first communication flowcharacteristics, while the second wireless communication channel hassecond communication flow characteristics. The first and second radiotransceivers participate on the first and second wireless communicationchannels, respectively. Therein, each of the plurality of wirelessroaming devices comprises a second processing circuit and means forselectively participating on the first and second wireless communicationchannels.

The access point may also comprise a wired communication interfacecircuit coupled to the first processing circuit that may itself comprisea first and a second microprocessor. Additionally, at least one of theplurality of wireless roaming devices may participate on the firstwireless communication channel while the other of the plurality ofwireless roaming devices participates on the second wirelesscommunication channel. Although the at least one of the plurality ofwireless roaming devices may participate on the first wirelesscommunication channel as directed by the access device, other variationsand combinations are also possible. For example, at least one of theplurality of wireless roaming devices may participate on the firstwireless communication channel to exchange a specific type of data,and/or may participate based on current channel conditions. Suchparticipation may be based the fact that, in some embodiments, thesecond wireless communication channel is more deterministic than thefirst wireless communication channel.

In any of the aforementioned embodiment, the communication network maycomprise at least a second access point. Other variations and aspects ofthe present invention will become apparent to ones of ordinary skill inthe art after reviewing the entire specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a high reliability access pointin accordance with the present invention.

FIG. 2 is a schematic representation of another high reliability accesspoint of the present invention utilizing an antenna diversity scheme ateach wireless adapter.

FIG. 3 is a representation of a distribution network for a wireless LANsystem utilizing high reliability access points.

FIG. 4 is a schematic representation of a high reliability access pointwith a backup power supply.

FIG. 5 is a schematic representation of a remote high reliability accesspoint connecting to the distribution network.

FIG. 6 is block diagram illustrating an embodiment of an access pointbuilt in accordance with the present invention which includes two radiosand a wired network interface, a first one of the radios operable on afirst channel and a second one of the radios operable on a secondchannel.

FIG. 7 a is a block diagram illustrating an embodiment of a portabledata terminal according to the present invention, the portable dataterminal having a single PCMCIA card that contains two radios, a firstone of the radios operable on the first channel and a second one of theradios operable on the second channel.

FIG. 7 b is a block diagram illustrating an alternative embodiment ofthe portable data terminal of FIG. 7 a, wherein the single PCMCIA cardincludes a single radio operable on the first charnel and the secondchannel and controlled by the processing circuitry.

FIG. 8 is a block diagram illustrating an alternative embodiment of aportable data terminal according to the present invention, the portabledata terminal having a single PCMCIA card that contains a multi-channelwireless transceiver and a wired network interface.

FIG. 9 is a diagram illustrating a communication system built andoperating according to the present invention, the communication systemincluding at least one access point having multiple radios, portableterminals having multiple radios and portable terminals havingmulti-channel radios.

FIG. 10 is a diagram illustrating a communication system built andoperating according to the present invention wherein one of the accesspoints facilitates communication between portable terminal unitsoperating on different channels within its cell by routing communicationbetween two of its radios.

FIG. 11 is a block diagram illustrating an embodiment of a communicationsystem according to the present invention wherein an access point uses adedicated control/busy channel transmitter to manage transmissionsbetween the access point and a plurality of roaming portable dataterminals within its cell.

FIG. 12 is a drawing illustrating advantageous operation of the accessdevice and portable data terminals of FIG. 11 when two roaming terminalsencounter hidden terminal conditions.

FIG. 13 is a block diagram illustrating an alternate embodiment of thecommunication system of the present invention wherein an access pointincludes a dedicated control/busy channel transceiver and roaming dataterminals communicate with the access point using either frequencynimble multi-channel transceivers or dedicated control/busy channeltransceivers.

FIG. 14 a is a block diagram illustrating a communication system of thepresent invention wherein access points and portable data terminalsoperate on a deterministic first channel and a non-deterministic secondchannel and the system routes communications on the channels based uponsystem conditions.

FIG. 14 b is a diagram illustrating operation of a communication systemof the present invention having both wired and wireless communicationcapability that includes at least one access point providingcommunication over a deterministic, time bounded first channel and anon-deterministic, contention access second channel.

FIG. 15 is a diagram illustrating the use of the access points andportable data terminals of FIG. 14 a wherein the system routes varioustransmissions within the network system according to system conditionssuch as channel activity, data type and data priority.

DETAILED DESCRIPTION

Referring now to the drawings wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1shows a high reliability access point 10 built in accordance with thepresent invention. An access point is a base station on a wireless localarea network with which roaming portable or mobile computer devices canconnect and communicate. The access point is typically part of anoverall distribution network which is connected to a host computer orentire computer local area network (LAN). The access points and theinfrastructure make up the distribution network and allow forcommunications between the roaming computer devices and the hostcomputer or entire computer local area network (LAN).

A high reliability access point 10 of the present invention includes acentral processing unit CPU processor 13 and at least two wirelessadapters 15 and 16. Each of the wireless adapters 15 and 16 include aradio 17 and 18, a media access control (MAC) processor 19 and 20 and anantenna 21 and 22, respectively. The radios and antennas are used for RFtransmission and reception. The MAC processor controls low levelprotocol functions including controlling the operation of the radio,radio channel, error control, e.g., ARQ or Selective Response, andcommunication with the CPU processor 13. The CPU processor 13 controlsthe high-level communications protocol functions and controls theinterface 25 between the high reliability access point 10 and theinfrastructure 26. In a preferred embodiment there is a PCMCIA standardinterface between the wireless adapters and the access point.

The distribution network is comprised of all of the access points andthe infrastructure which connects all of the access points. A hostcomputer or an entire host network is connected to the distributionnetwork. The distribution network allows computer devices to communicatewith the host computer or host network.

The division between what is high level protocol, and thus handled bythe CPU processor, and what is low level protocol and thus handled bythe MAC processor, can vary greatly depending upon the intelligencelevel of the MAC processor. In a preferred embodiment, theinfrastructure conforms to an industry standard wired LAN such asEthernet. The MAC processor can be made very intelligent and thereforecapable of handling a great deal of radio specific protocol. On theother hand, the MAC processor can be minimally intelligent and handleonly the most basic protocol functions allowing the CPU processor tohandle the majority of the protocol functions.

Utilizing multiple wireless adapters in a single access point, as wellas incorporating independent intelligence and low level protocolresponsibility into each wireless adapter, yields several significantadvantages. The examples depicted in FIGS. 1-4 show access points usingonly two wireless adapters per access point. Utilizing two wirelessadapters in the manner discussed below will greatly increase thereliability of a particular access point, as well as increase thereliability of the entire distribution network. Access points could usemore than two wireless adapters and the utilization of the multiplewireless adapters would be similar to the implementation describes usingonly two wireless adapters with addition protocol being required tohandle the increased redundancy and to allow for more sophisticated selfmonitoring.

Referring still to FIG. 1, the CPU processor 13 can designate the RFaddress to which each wireless adapter 15 and 16 is to respond. The CPUprocessor 13 can, but need not, assign the same address to each wirelessadapter. Therefore, in one configuration, the CPU processor 13 candesignate that each of the wireless adapters 15 and 16 respond to theaddress assigned to that access point 10. Designated as such, bothradios 17 and 18 will be operating simultaneously on the same channel.In a frequency hopping system, both radios 17 and 18 would be operatingon the same hopping sequence, and be mutually synchronized to thathopping sequence.

Accordingly, the wireless adapters 15 and 16 are configured to receiveincoming transmission from roaming computer devices within range. Asboth wireless adapters 15 and 16 receive the transmission, each adaptercan evaluate the quality information to the CPU processor 13. The CPUprocessor 13 uses the quality information to determine which wirelessadapter is receiving the higher quality signal. The CPU processor 13will then typically choose to receive the incoming transmission on thewireless adapter with the higher signal quality and respond using thesame adapter.

The antennas 21 and 22 can be positioned to allow the access point 10 toimplement an antenna diversity scheme which will help reduce thenegative effects caused by multipath interference. Antenna diversity canbe accomplished in various ways. For example, the antennas can be placedsufficiently far apart, typically greater than a quarter wavelengthapart, or the antennas can be positioned at a 90 degree angle withrespect to each other to create a polarization antenna diversity scheme.

With an antenna diversity scheme in place, the signal from a wirelesscomputer device will be received differently on each antenna due tomultipath signal propagation. Therefore, each wireless adapter mayreceive a signal of a different quality. The CPU processor 13 can choosewhich wireless adapter to use based upon the quality of the receivedsignal. Each wireless adapter includes the capability of measuringsignal quality and only good messages will be forwarded on to the CPUprocessor 13. The quality can be appended to the message or can bepresented to the CPU in a memory register.

Referring now to FIG. 2, another high reliability access point 20 builtin accordance with the present invention is shown. In this embodiment,in addition to having an antenna diversity scheme at the access pointlevel, there is an antenna diversity scheme at the wireless adapterlevel. Each wireless adapter 15 and 16 includes at least two antennas 21and 23, 22 and 24, respectively positioned to create an antennadiversity scheme. Thus for the wireless adapter 15 the antennas 21 and23 are either positioned sufficiently far apart, more than a quarterwavelength, or the antennas 21 and 23 are positioned in an asymmetricalor orthogonal manner to provide polarization diversity. The antennas 22and 24 for the wireless adapter 26 are placed in a similar manner.

In this embodiment, an incoming signal is received on both antennas 21and 23 of the wireless adapter 15. The MAC processor 19 then determinesthe quality if the signal coming in on each of the antennas 21 and 23connected to the wireless adapter 15. Based upon the signal qualityinformation, the MAC processor 19 will choose which of the antennas 21and 23 to use to receive the incoming transmission. The MAC processorwill also forward the signal quality information regarding the selectedantenna to the CPU processor 13. The wireless adapter 16 will perform asimilar process and forward the signal quality information for its bestantenna to the CPU processor 13. The CPU processor 13 can then determinewhich wireless adapter is receiving the highest quality signal and usethat wireless adapter to receive the incoming transmission and respondto the transmitting station.

When a high reliability access point wishes to transmit a message, suchas an acknowledgment of a received message, to a roaming computerdevice, the CPU processor 13 will utilize the received quality signalinformation to determine which wireless adapter to use to send themessage. Likewise, if the wireless adapter is utilizing an antennadiversity scheme it will also select the most appropriate antenna fortransmitting a message.

While one of the wireless adapters is transmitting, the other wirelessadapter can operate as a promiscuous listener to determine if thecorrect message is being sent. For example, referring to FIG. 1, if theCPU processor 13 is sending a message to a roaming computer device viawireless adapter 16, wireless adapter 17 can operate in the receive modeand monitor the message being sent by the wireless adapter 16. Thisprovides a local loop back capability and allows the access point toperform self-monitoring. If the CPU processor 13 determines that one ofthe wireless adapters is not operating correctly, the malfunctioningwireless adapter can be disabled. Additionally, the CPU processor 13 canthen send a message to the system management portion of the host networkvia the infrastructure 26 that it has a defective wireless adapter andrepairs are needed.

Referring again to the configuration in which each of the wirelessadapters is listening on the same channel, another advantage achieved bythis configuration is the ability to receive two concurrent messages. Inan access point that only contains one adapter, this situation willcause a collision and neither message will be received. In a highreliability access point built in accordance with the present invention,it is possible that the one wireless adapter will be able to receive oneof the messages while the other wireless adapter receives the other, dueto multipath fading at each of the wireless adapter antennas.

Referring now to FIG. 3, a portion of a distribution network 30utilizing high reliability access points is shown. The distributionnetwork 30 includes an infrastructure 33 and two high reliability accesspoints 35 and 36. Access point 35 includes a CPU processor 37 and twowireless adapters 38 and 39. Access point 36 includes a CPU processor 41and two wireless adapters 42 and 43. In the present example, a break 45in the infrastructure 33 has occurred. Access point 35 is upstream tothe break with respect to the host computer network and thus is notimmediately affected by the break 45. However, access point 36 isdownstream to the break 45 and therefore is no longer connected to thehost computer network.

When a situation like this occurs, the downstream access point 36 willbegin attempting to communicate with an upstream access point usingwireless communication. In this example, the upstream access point isaccess point 35. However, the communication need not be with the accesspoint immediately upstream, the only requirement is that it be with anaccess point which is upstream with respect to the break. The hostcomputer network or other access points will previously have shared thelogistic and address information concerning all of the access points toeach access point in the distribution network.

Once communications with an upstream access point 35 is established,each access point 35 and 36 will dedicate one of its wireless adapters39 and 42, respectively to provide a wireless repair of the break 45 inthe infrastructure 33. When this happens, the CPU processor for each ofthe access points will instruct the dedicated wireless adapter to changeso that it is no longer operating on the same channel as the otheradapter in the access point.

A communication channel between access points is established. Thededicated wireless adapters 39 and 42 will no longer be used to transmitor receive information to or from roaming computer devices. However, thenon-dedicated wireless adapters 38 and 43 will communicate with theroaming computer devices. Once the top priority of reestablishingcommunications between all of the access points in the distributionnetwork 30 and the host computer network has been accomplished, theaccess points can then send a message to the system management portionof the host computer network detailing where the break (or breaks)exists.

It is conceivable that the distribution network could lose its entireinfrastructure. In this case, each of the high reliability access pointswould dedicate one of its wireless adapters to network infrastructurecommunications while retaining one of its wireless adapters forcommunication with roaming computer devices. Using the same techniquedescribed above, a temporary or remote access point could be establishedthat, intentionally, is not connected to the infrastructure. Thisconfiguration is discussed below in greater detail with reference toFIG. 5. The use of directional gain antennas for the dedicated wirelessadapter would allow the temporary or remote access point to bepositioned a considerable distance from the infrastructure.

Referring now to FIG. 4, a high reliability access point 50 with abackup power supply 52 is shown. Typically, the access point will bewired to an external power source 54 such as a wall outlet. However,there is a great desire that if power is lost that the distributionnetwork not shut down since the roaming computer devices will normallynot be dependent upon the external power source 54. In this embodimentof the present invention, the back-up power source 52 is wired inparallel with respect to the external power source 54. Thus, if theexternal power source 54 fails, the access point 50 will not lose power.

Referring now to FIG. 5, a remote access point 70 is shown connecting tothe infrastructure 33 by means of dedicated wireless adapters 62 and 72.The access point 70 is not hard wired to the infrastructure 33.Therefore, the access point dedicates one of its wireless adapters 72 tonetwork infrastructure communication. The other wireless adapter 74continues to communicate with roaming computer devices within the rangeof the access point 70. An access point 60 that is hard wired into theinfrastructure 33 dedicates one of its wireless adapters 62 to networkinfrastructure communication and establishes a link between theinfrastructure 33 and the remote access point 70. The access point 60can continue to service the roaming computer devices within its rangethrough the wireless adapter 64.

The hard wired access point 60 that is used to connect the remote accesspoint 70 to the infrastructure need not be the access point that isphysically closest to the remote access point 70. Use of the directionalantenna would allow a remote access point to establish communicationwith virtually any of the access points that are hard wired to theinfrastructure.

Additionally, several remote access points could establish wirelessinfrastructure communication by each dedicating one of their wirelessadapters. In this arrangement, only one of the remote access points needbe in communication with a wired access point. All other remote accesspoints could establish communication with the host computer network viathe remote access point in communication with a wired access point.

FIG. 6 is block diagram illustrating an embodiment of an access point600 built in accordance with the present invention capable ofcommunicating with wireless devices in its cell on both a first channeland a second channel. The access point 600 thus includes a first radio616 operating on a first channel and a second radio 608 operating on asecond channel. The access point also includes a processing unit 612 andadditional circuitry 614, both of which couple to the first radio 616,the second radio 608 and a wired Ethernet transceiver through a businterface 610. The wired transceiver 606 allows the access point 600 toaccess a wired LAN backbone 622 to which various other system componentsmay connect. The wired LAN backbone may include, for example, anethernet network, a token-ring network or an asynchronous transfer mode(ATM) network among other network types. In any such case, the wiredtransceiver 606 facilitates communication between the access point 600and devices coupled to the wired LAN backbone 622.

The blocks illustrated in FIG. 6 are simplified for exemplary purposes,and it will be understood by one skilled in the art that an access point600 according to the present invention is not limited to the blockcircuitry shown in FIG. 6. In another embodiment, the access point 600may contain additional transceivers for communicating on other channels,over other mediums and in other networks as well.

The first channel radio 616 couples to first antenna 618 while thesecond channel radio 608 couples to second antenna 620. The antennas 618and 620 may either be protruding or non-protruding antennas, dependingupon system requirements. The first channel radio 616 and the secondchannel radio 608 operate independently to form a first communicationcell and a second communication cell, respectively. When a radius of thefirst communication cell substantially equals a radius of the secondcommunication cell, the cells substantially overlay one another.However, when the radii of the communication cells differ, the largercell fully overlays and extends beyond the smaller cell. The first andsecond channels may operate using different frequencies, modulationschemes and code spreading schemes. The selections of such operationalchannel variations depend on overall system constraints, yet shouldresult in two independent channels that do not interfere with oneanother unacceptably.

The bus interface 610 isolates the processing unit 612 and theadditional circuitry 614 of the access point 600 from the operatingcharacteristics of the radios 616 and 608 and the wired transceiver 606.Thus, communication with any of the transceivers can be accommodated bygeneral circuitry and software routines of the access point 600. In oneembodiment, the bus interface 610 is a PCI bus interface with the firstchannel radio 616, second channel radio 606 and wired transceivercompatible with PCI bus standards. However, in other embodiments,differing interface standards may be employed.

In operation, the processing unit 612 is programmed with the networkconfiguration to route communications through the first channel radio616, the second channel radio 608 and the wired transceiver 606.However, roaming portable units may alter the network configuration asthey move between cells. Thus, the access point 600 periodically pollsdevices within its communication cell to update the networkconfiguration. Updates are entered and forwarded for other units in thesystem.

Incoming messages received via the wired transceiver 606 may be stored,displayed and routed via the first channel radio 616 or routed via thesecond channel radio 608 to portable data terminals or other wirelessdevices operating within the cell(s) of one or more of the access point600. Similarly, an incoming message on one of the radios 616 or 608 maybe stored, displayed, routed through one of the radios 616 or 608 orrouted through the wired transceiver 606, depending upon the messagedestination and type.

By providing routing within the access point 600 between the firstchannel radio 616 and the second channel radio 608, message delivery isexpedited. Further, as will be described herein, by providing two radiosin various access points, fewer cells may be required to adequatelyservice a premises such as a factory. Moreover, when one of the radiosis employed to provide control within a cell while the other radioprovides primary communication within the cell, collisions betweendevices may be eliminated Still further, when one of the radios providesa deterministic communication path while another one of the radiosprovides a non-deterministic communication path, data and messagetransmissions within the network may be controlled to satisfy bandwidthrequirements of the various devices within the system. It may bepreferable to utilize a deterministic communication path for some typesof communications such as telephony video or real-time data transfer,for example. However, when the preferred deterministic path isunavailable for some reason, the alternative non-deterministic path maystill be used.

The access point 600 may synchronize transmissions on the first channelradio 616 and the second channel radio 608 to avoid unacceptableconflicts between transmissions on one radio and receipts on the otherradio. In this fashion, unacceptable conflicts are minimized.

FIG. 7 a is a block diagram illustrating an embodiment of a portabledata terminal 720 according to the present invention, the portable dataterminal having a single PCMCIA card that contains two radios. Inparticular, the portable data terminal 720 contains terminal circuitry722 that includes processing circuitry 726, conventional terminalcircuitry 728 and interface circuitry 730. The interface circuitry 730provides a PCMCIA interface for receiving PCMCIA cards of variousfunctionality. Terminal circuitry 722 is well known and can be found inconventional portable or hand held computing devices.

Via the interface circuitry 730, the portable data terminal 720 acceptsPCMCIA cards. As illustrated, the PCMCIA card inserted constitutes acommunication module 724 that provides wireless access on two channels.Specifically, the communication module 724 comprises processingcircuitry 732, first channel radio 735, second channel radio 734 andinterface circuitry 744. The first channel radio 735 communicates viafirst antenna 737 while the second channel radio 734 communicates viasecond antenna 738. Configured and operable in this manner, the portabledata terminal 720 may communicate with the access point 600 of FIG. 6 oneither the first channel or the second channel.

Independent of whether the first channel radio 735 or the second channelradio 734 is used, the processing circuitry 726 delivers and receivesdata and messages via the interface circuitry 730 in the same manner andformat, i.e., the interface circuitry 730 supports a commoncommunication interface and protocol. The processing circuitry 732 ofthe communication module 724 receives data and messages via theinterface circuitry 744. The processing circuitry 732, including a DSP742, participates to assist in wireless communication via both the firstchannel radio 735 and the second channel radio 734. Thus, the module 724not only saves on PCMCIA slots, but also saves costs and increasesreliability by sharing common circuitry resources. In particular, thefirst channel radio 735 and second channel radio 734 share the interfacecircuitry 744 and processing circuitry 732 which includes the DSP 742.In another embodiment of the portable data terminal 720, a PCMCIAcompatible wired network adapter could be installed which would alsoshare some of the common circuitry resources.

FIG. 7 b is a block diagram illustrating an alternative embodiment of aportable data terminal 748 that receives a single PCMCIA card having aradio 750 that includes two separate radio units. As contrasted to thedual radio design of the portable data terminal 720 of FIG. 7 a, theradio 750 of the portable data terminal 748 of FIG. 7 b operates on boththe first channel and the second channel. The radio 750 is coupled toantenna 756 and controlled by processing circuitry 752 that includesdigital signal processing circuitry 754. The radio 750 includes a firstradio unit operable on the first channel and a second radio unitoperable on the second channel with the radio units sharing some commoncomponents.

The processing circuitry 752 may control operation of the radio 750 in asimplex fashion such that the radio 750 operates on the first channel asrequired and operates on the second channel as required. Because theradio 750 may includes circuitry shared by the radio units, the radio750 may only operate on one channel at a given time. By multiplexing itsoperation over time, however, the radio 750 provides sufficient coverageon the channels at a reduced cost. Other components of the portable dataterminal of FIG. 7 b were previously described with reference to FIG. 7a and will not be further described herein.

FIG. 8 is a block diagram illustrating an alternative embodiment of aportable data terminal 800 according to the present invention, theportable data terminal 800 having a single PCMCIA card that contains amulti-channel (or multi-mode) wireless transceiver 739 and a wirednetwork interface 736 (or modem transceiver). The portable terminal 800includes terminal circuitry 722 and a module 802 including variouscomponents previously described with reference to FIG. 7 a. The terminalcircuitry 722 includes processing circuitry 726, conventional terminalcircuitry 728 and interface circuitry 730. The communication module 802includes processing circuitry 732, the multi-mode wireless transceiver739, the wired modem transceiver 736 and interface circuitry 744. Whenin use, the wired modem transceiver 736 interfaces via a jack 740 to atelephone line (not shown). Similarly, the wireless multi-modetransceiver 739 communicates via an antenna 741.

The processing circuitry 732 of the communication module 802 receivesdata and messages via the interface circuitry 744. If the modemtransceiver 736 is being used, the processing circuitry 732appropriately (de)segments and (de)compresses the data/messagesutilizing a digital signal processor (DSP) 742. Otherwise, theprocessing circuitry 732, including the DSP 742, participate to assistin wireless communication via the multi-mode transceiver 739. Thus, themodule 802 not only saves on PCMCIA slots (as required when aconventional radio card and a conventional modem card are both beingused), but also saves costs and increases reliability by sharing commoncircuitry resources.

The multi-mode transceiver 739 is frequency nimble and may operate invarious modes, such as those that may be used with a frequency spreadingscheme such as those described in U.S. Pat. No. 5,425,051 issued Jun.13, 1995 to Ronald L. Mahany, which is incorporated herein by reference.Thus, the multi-mode transceiver 739 may operate on both the firstchannel and the second channel and communicate with the access point 600of FIG. 6 on either the first channel or the second channel. As will befurther described herein, operation on differing channels may beemployed to reduce installed system component requirements, to alleviatevarious potential interfering operating conditions and to moreefficiently route data and messages within the wireless local areanetwork.

FIG. 9 is a diagram illustrating a communication system 900 built andoperating according to the present invention. The communication systemincludes an access point 902 operating on two channels and access points904 and 906 operating on a single channel. Each of the access points902, 904 and 906 connects to a wired LAN backbone 908 to facilitatewired communication between the access points and computer systems 910and 912 connected to the wired LAN backbone 908.

Access point 902 includes both a first channel radio and a secondchannel radio. In the embodiment illustrated, the first channel radiocreates a first channel cell 930 extending with a first channel radiusabout the access point 902. The second channel radio of the access point900 creates a second channel cell 932 extending with a second channelradius about the access point 902. As illustrated, the second channelcell 932 has a larger radius than the radius of the first channel cell930. To create the relatively larger cell, the second radio may operateat a higher power, operate at a lower data rate or operate in anotherdiffering manner to create the relatively larger cell.

Access points 904 and 906 generate first channel cells 934 and 936,respectively. Portable data terminals 920, 922, 924 and 926 and scanningunit 918 communicate with the various access points 902, 904 and 906 androam about the communication system 900, potentially moving from cell tocell. Other devices, such as stationary printers 914 and 916 typicallyremain within one cell of the communication system 900. In theembodiment illustrated, portable data terminals 920 and 926 includemulti-mode radios while portable data terminals 922 and 924 include botha first channel radio and a second channel radio. However, in otherembodiments, some of the portable data terminals may only on one of thechannels.

As illustrated, terminal 922 includes a first channel antenna 940 and asecond channel antenna 942 while access point 902 includes both a firstchannel antenna 944 and a second channel antenna 946. Thus, whenever theterminal 922 roams within the second channel cell 932, the terminal 922communicates via a second channel radio and second channel antenna 942.Further, terminal 950 may communicate with access point 902 on the firstchannel via its first channel antenna 954 when resident within the firstchannel cell 903. Finally, terminal 952, having a single radio operablethe first channel via antenna 956 may communicate with access point 902on the first channel when resident within the first channel cell 932.

As shown, portable data terminal 922 resides both within the firstchannel cell 930 and the channel cell 932 generated by access point 902.Thus, the portable data terminal 922 may communicate with access point902 on either the first channel or the second channel. However, printer916 and scanning unit 918 reside only within the second channel cell 932generated by access point 902 and must communicate with the access point902 on the second channel.

Print data originating at computer 910 and intended for printer 916travels from computer 910, through the wired LAN backbone 908 to accesspoint 902 and across first channel cell 932 to the printer 916. Duringthis transmission, the data is routed through the wired LAN backbone andthe wireless network based upon the network locations of the computer910 and the printer 916. The combination of these segments forms aunique network path. However, a message moving from portable dataterminal 926 to portable data terminal 922 may be routed along twodifferent network paths. While both network paths include access point906, wired LAN backbone 908 and access point 902, one network pathincludes first channel cell 930 while the other network path includessecond channel cell 932. Thus, depending upon system conditions and thesystem configuration, the message is routed via one of the two networkpaths. Such conditions may include cell traffic, required data rates andother factors.

FIG. 10 is a diagram illustrating a communication system 1000 built andoperating according to the present invention wherein one of the accesspoints routes communication between two portable terminal unitsoperating on different channels within its cell. In the communicationsystem 1000, both a first access point 1002 and a second access point1004 include both first and second channel radios. The first accesspoint 1002 generates a first channel cell 1006 and a second channel cell1008 within which portable data terminals 1012 and 1014 operate.Further, second access point 1004 generates a first channel cell 1010and a second channel cell 1011 within which portable data terminals 1012and 1014 may operate. In the embodiment, the system 1000 prefers toroute communication on the first channel due to its characteristicsalthough the portable data terminals may operate on either channel.

As illustrated, portable data terminal 1012 resides within both thefirst channel cell 1006 and the second channel cell 1008 generated byaccess point 1002. However, portable data terminal 1014 resides onlywithin the second channel cell 1008 of the access point 1002. Thus, inthe transmission of a message from portable data terminal 1012 toportable data terminal 1014, access point 1002 receives the message fromportable data terminal on the first channel radio and transmits themessage to portable data terminal 1014 on the second channel. Withreference to FIG. 6, the processing unit 612 receives the message viathe first channel radio 616 across the bus interface 610. The processingunit 612 determines the destination of the message, and routes themessage back across the bus interface 610 to the second channel radio608 that transmits the message to portable data terminal 1014. Accesspoint 1004 also provides multiple channel routing of messages betweenportable data terminals 1016 and 1018.

Without the multiple channel communication capabilities of thecommunication system 1000, an additional access point 1020 having afirst channel cell 1022 would be required to facilitate communicationwith portable data terminals 1014 and 1018. The cost of such anadditional access point 1020 would not only include the cost of theaccess point 1020 itself but the expense of connecting the access point1020 to the wired LAN backbone 908 and AC power.

The cost of such addition would far exceed the cost of the secondchannel radios in access points 1002 and 1004. Furthermore, in someinstallation, extensions of the wired LAN backbone 908 are not possible.Even if such access point 1020 were installed the exemplarycommunication would require routing of messages between portable dataterminal 1012 and 1014 across the wired LAN backbone 908. Suchadditional loading slows operation of the wired LAN backbone 908 anddecreases system performance.

FIG. 11 is a block diagram illustrating an embodiment of a communicationsystem 1100 according to the present invention wherein an access point1102 uses a dedicated control/busy channel transmitter 1114 operating ona busy/control channel to manage transmissions between the access point1100 and a plurality of roaming portable data terminals 1104 and 1106within its cell. The communication system may also contain wiredcommunication to a wired Ethernet backbone LAN 908.

The access device 1102 includes control circuitry 1120, a datatransceiver 1118, a busy/control transmitter 1114 and antennas 1115 and1117. The data transceiver 1117 supports communication on acommunication channel (first channel) between the access point 1102 andwireless network devices operating within range of the access point,such as the portable data terminals 1104 and 1106. Further, thebusy/control transmitter 1114 supports transmissions on the busy/controlchannel (second channel). The Ethernet transceiver 1115 supportscommunication between the backbone LAN 908 and the control circuitry1120.

Portable data terminals 1104 and 1106 include terminal circuitry 1112, adata transceiver 1108 that communicates on the communication channel viaantenna 1109 and a busy/control receiver 1110 that receives busy/controlinformation via antenna 1111. As previously described, the communicationchannel and the busy/control channel are non-convergent and may operateconcurrently in a single area or location. However, the access point1102 must operate so as not to interfere with incoming transmissions byconcurrently initiating a transmission. Thus, in one embodiment,transmissions on the communication channel and the control/busy channelare synchronized to prevent such conflicts.

The access point 1102 employs the busy/control transmitter 1114 tocontrol operations within the first wireless network cell. In oneembodiment, the access point 1102 periodically transmits controlparameters that the portable data terminals 1104 and 1106 use tosynchronize with communications on the communication channel Forexample, with the data transceiver of the communication channeloperating in a spread spectrum mode, the busy/control transmitter 1114transmits code spreading sequences, frequency hopping parameters andother operating parameters that allow the portable data terminals 1104and 1106 to communicate within the cell on the communication channel.Such control information may be intermittently transmitted by the accesspoint 1102 or may be continuously transmitted.

Additionally, the access point 1102 transmits a busy signal on thebusy/control transmitter 1114 to authorize communication within thecell. To prevent portable data terminal 1104, for example, fromtransmitting while portable data terminal 1106 is communicating with theaccess point 1102, the access point 1102 transmits a busy signal on thebusy/control channel using the busy/control transmitter 1114. Theportable data terminal 1104 receives the busy signal and does nottransmit information while such busy signal is active, perhaps enteringa sleep mode instead and waking up periodically to determineavailability The busy signal may include a continuous transmission orperiodic transmission. However, in both embodiments, portable dataterminals 1104 and 1106 listen with their respective control/busyreceivers 1110 prior to initiating communication with the access point1102. Thus, upon roaming into range of the wireless access device 1102,the portable data terminals 1104 do not interfere with ongoingcommunication.

FIG. 12 is a drawing illustrating advantageous operation of the accessdevice and portable data terminals of FIG. 11 when two roaming terminalsencounter hidden terminal conditions. In particular, each of theportable data terminals 1208 and 1212 is configured to listen on thebusy/control channel and to communicate on the communication channelonly when the communication channel is clear (available). In thisconfiguration, when no desire to communicate is present, the portabledata terminals 1208 and 1212 need only occasionally check thebusy/control channel to identify any outstanding messages orcommunication requests as transmitted by the access device 1202. Ifeither portable data terminal 1208 or 1212 desires to participate on thecommunication channel (to initiate communication or to respond toawaiting messages or communication requests), that terminal need onlymonitor the busy/control channel long enough to identify that thecommunication channel is clear before responding to a poll on thecommunication channel. As before, the wireless access device 1202 mayalso periodically identify the communication channel mode and associatedparameters as selected and reselected by the wireless access device1202.

To fully appreciate this process, first assume that the portable dataterminals 1208 and 1212 are not within range of the wireless accessdevice 1202. Upon wandering within range of the access device 1202, theportable data terminal 1212 begins listening for transmissions on abusy/control channel. Within some time period thereafter, the accessdevice 1202 participates on the busy/control channel to transmit currentchannel conditions and optionally, the currently selected communicationchannel definition (i.e., mode and parameters) and/or pending messageand communication request indicators. After identifying a need toparticipate, the portable data terminal 1212 awaits a transmission fromaccess device 1202 (on the busy/control channel) that the selectedcommunication channel is clear (not in use). When the channel is clear,the portable data terminal 1212 begins participating thereon.

Second, assume that, while the portable data terminal 1212 is engaged inongoing communication with a computing device 1206 on a backbone LAN 908via the access device 1202, the portable data terminal 1208 comes withinrange of the access device 1202 and desires to participate on thecommunication channel. The portable data terminal 1208 adapts itself toparticipate on the busy/control channel and identifies, in periodictransmissions from the access device 1202, that the communicationchannel is busy. Thus, the portable data terminal 1208 must monitor thebusy/control channel to identify when the communication channel is clearbefore participating on the communication channel.

This operation works whether or not the portable data terminals 1208 and1212 are within range of each other. In particular, portable dataterminal 1208, portable data terminal 1212 and access device 1202 havetransmission ranges illustrated by dashed circles 1210, 1214 and 1204,respectively. Although both portable data terminals 1208 and 1212 arewithin range of the access device 1202, neither are in range of eachother and, thus, are referred to as “hidden” from each other. The accessdevice 1202 is within range of both of the portable data terminals 1208and 1212. If the portable data terminal 1208 attempted to transmit onthe communication channel while the portable data terminal 1212 wastransmitting, a collision would occur at the wireless access device1202. However, this is not the case because both of the portable dataterminals 1208 and 1212 must receive a communication channel clearindication on the busy/control channel from the access device 1202 thatis in range of both, avoiding the hidden terminal problem. Whenparticipation is completed on the communication channel, the portabledata terminals 1208 and 1212 resume monitoring of the busy/controlchannel.

Participation by the access device 1202 on the busy/control channel needonly be by transmitting, although receiving might also be employed incase the busy/control channel is to be shared. Similarly, participationby the portable data terminals 1208 and 1212 need only be by receivingtransmissions, although transmitting might also be employed. Inparticular, transmission might be employed by a wireless terminal on thebusy/control channel if the wireless terminal does not support thecurrently selected communication channel, i.e., does not support themode and associated parameters.

FIG. 13 is a block diagram illustrating an alternate embodiment of thecommunication system 1300 of the present invention wherein an accesspoint 1302 includes a dedicated control/busy channel transceiver 1310and roaming data terminals 1304 communicate with the access point 1302using either frequency nimble multi-channel transceivers 1305 or adedicated control/busy channel transceiver 1326. Thus, the communicationsystem 1300 facilitates bi-directional communication on the busy/controlchannel so that the access point 1302 may optimize operation of thesystem 1300.

In addition to the busy/control transceiver 1310 coupled to antenna1314, the access point includes control circuitry 1306, a datatransceiver 1312 coupled to antenna 1316 that facilitates wirelesscommunication on the communication channel and an Ethernet transceiver1308 that couples the access point 1302 to the backbone LAN 908.Portable data terminal 1304 includes terminal circuitry 1112 and amulti-mode/multi-channel transceiver 1305 that allows the portable dataterminal 1304 to communicate both on the busy/control channel and thecommunication channel. Portable data terminal 1320 includes terminalcircuitry 1322, a busy/control transceiver 1324 coupled to antenna 1330that allows the portable data terminal 1320 to communicate on thebusy/control channel and a data transceiver 1326 coupled to antenna 1328that allows the portable data terminal to communicate on thecommunication channel.

Having separate radio units and antennas, the access device 1302participates on: 1) a selected communication channel, servicing dataexchanges in the communication network cell; and 2) the busy/controlchannel defined by predetermined mode and parameter information known toall wireless transmitters, controlling access to the selectedcommunication channel. Such participation is often simultaneous,preventing a portable data terminal 1304 or 1320 from having to waitlong on the busy/control channel for a transmissions. Within apredefined maximum time period, the portable data terminal 1304 or 1320receives transmissions from the access device 1302 identifying currentlyselected communication channel mode and associated parameters, shouldsuch be required. The access device 1302 periodically broadcasts suchinformation on the busy/control channel to capture terminals that happento need communication channel definitions (e.g., selected mode andparameters) to participate. The portable data terminal 1304 utilizes theidentified mode and associated parameter information to switch themulti-mode transceiver 1305 over to the selected communication channeland begins participation thereon. Portable data terminal 1320 may alsoalter the operation of the data transceiver 1326 based upon the receiptfrom the access point 1302.

In operation, the wireless terminal 1304 participates on thebusy/control channel except when it has a need to gain access to theselected communication channel. Thus, its operation in the system 1300is satisfactory. By including only the terminal circuitry 1112 and oneradio, the portable data terminal is less costly than the multi-radioportable data terminal 1320. However, because the wireless terminal 1320includes two radios, the portable data terminal 1320 may place the datatransceiver 1326 in a low power state, and only power up thebusy/control channel transceiver 1324 to check in. Thus, portable dataterminal 1320 may consume less power that portable data terminal 1304.

FIG. 14 a is a block diagram illustrating a communication system 1400according to the present invention wherein an access point 1402 andportable data terminals 1404 and 1406 operate on a deterministic firstchannel and a non-deterministic second channel and the system 1400routes communications on the channels based upon system conditionsand/or the requirements of a particular communication. To carry out suchfunctionality, the access device 1402 may comprise control circuitry1408, a wired LAN transceiver 1410 and either a single, configurabletransceiver (for operating on both the deterministic andnon-deterministic channels, not shown) or a single transceiver 1412coupled to antenna 1413 for operating on the deterministic channel and asingle transceiver 1414 coupled to antenna 1415 for operating on thenon-deterministic channel.

In one embodiment, the deterministic channel allocates a particularcommunication bandwidth to each wireless device requiring communication,perhaps in a polled, token passing or time slotted implementation. Suchoperation may be required where many wireless devices reside within asingle cell and compete for communication with the access point 1402. Inthe embodiment, the access point 1402 also allows all devices within thecell to compete for available bandwidth on the non-deterministicchannel. However, the access point 1402 may provide overrides todynamically reallocate bandwidth in the deterministic channel and toassign bandwidth on the non-deterministic channel as may be required forthe particular operating conditions.

With a single multi-mode transceiver 1418 coupled to antenna 1419controlled by terminal circuitry 1416, the portable data terminal 1404operates on either the deterministic channel or the non-deterministicchannel at any time. Alternatively, portable data terminal 1406 havingterminal circuitry 1420, a deterministic transceiver coupled to antenna1425 and a non-deterministic transceiver 1422 coupled to antenna 1423communicate on both the deterministic channel and non-deterministicchannel simultaneously.

Independent of their differing constructions, the portable dataterminals 1404 and 1406 may determine which channel to operate upon.During data transfer operations wherein data transfer rates are notcritical, portable data terminal 1404 may determine that thedeterministic channel provides sufficient bandwidth. In that case, theportable data terminal 1404 configures its multi-mode transceiver 1418to operate on the deterministic channel. However, during voice messagetransfer operations, the portable data terminal 1404 may determine thatthe bandwidth of the deterministic channel is not satisfactory. In thatcase, the terminal circuitry 1404 would configure the multi-modetransceiver 1418 to operate on the non-deterministic channel.

FIG. 14 b is a diagram illustrating a communication system 1450according to the present invention that facilitates both wired andwireless communications. The communication system 1450 includes a wiredbackbone 1452 and at least one access point 1456 that supportscommunication over a deterministic, time bounded first wireless channeland a non-deterministic, contention access second wireless channel.Along with the access point 1456, the communication system 1450 may alsoinclude a PBX (Private Broadcast Exchange) system 1454, one or more of acomputer 1454, and other typical wired network devices interconnected bythe wired backbone 1452. Additionally, the communication system 1450comprises a plurality of wireless network devices, such as wirelessterminals 1470, 1472 and 1474, which may be portable hand-held devices,mobile computing devices, laptop computers, wireless peripherals, etc.

Communication upon the wired backbone 1452 may be accomplished accordingto various communication techniques. In one embodiment, communicationupon the wired backbone 1452 occurs via an STM (Synchronous TransferMode) protocol wherein the wired backbone 1452 serves as an STMbackbone. With the STM protocol, a particular bandwidth is provided foreach communication link established between a sending and a receivingdevice attached to the wired backbone 1452.

In another embodiment, communication upon the wired backbone 1452 iscarried out using an ATM (Asynchronous Transfer Mode) protocol in whichbandwidth between a sending and a receiving device on the wired backbone1452 is adjusted based upon immediate communication requirements. Insuch operation, the wired backbone 1452 serves as an ATM backbone.Operation according to the ATM protocol allows for variations in datatransmission bandwidths as is immediately required but that provides anaverage bandwidth over time.

The at least one access point 1456 provides a link between the wirelessand wired communications within the communication system 1450. Theaccess point 1456 includes a time bounded adapter 1458 connected to anantenna 1460 which provides wireless communication on the deterministic,time bounded first wireless channel governed by a first wirelessprotocol. The access point 1456 also includes a contention adapter 1462connected to an antenna 1464 which provides wireless communications onthe non-deterministic, contention access second wireless channelgoverned by a second wireless protocol. Alternatively, part or all ofthe circuitry underlying the adapters 1458 and 1462 may be combined intoa single unit to share common underlying functionality.

The wireless network device 1470 includes either a dual purposetransceiver or two transceivers for communicating on the first andsecond wireless channels via the first and second wireless protocols,respectively. A transceiver in the wireless network device 1472 onlysupports communication on the second wireless channel pursuant to thesecond wireless protocol. Likewise, a transceiver in the wirelessnetwork device 1474 supports communication on the first wireless channelpursuant to the first wireless protocol. For example, the wirelessnetwork device 1474 might comprise a portable phone unit operatingusing, e.g., PCS (Personal Communication Service) or other telephonyprotocol as the first wireless protocol.

Although direct communication is possible, to manage the first wirelesschannel, the at least one access point 1456 relays wirelesscommunication between the wireless network devices 1470 and 1474 if bothparticipate on the first wireless channel. If the at least one accesspoint 1456 is the only access point involved that services the twodevices 1470 and 1474, such relaying need not involve the wired protocolon the backbone 1452. If the device 1470 happens to communicate via thesecond wireless channel the access point 1456 internally translates andrelays communications between the devices 1470 and 1474. Similarly, ifthe device 1470 intends to communicate with a wired network device usingeither the first or second wireless protocol the access point 1456utilizes the first or second wireless protocols, respectively, tocommunicate with the device 1470. The access point 1456 alsocommunicates with the target wired network device, e.g., the computer1454, via the wired communication protocol. Relaying between the wiredand wireless channels also requires translation.

If more than one access point is coupled to the wired backbone 1452, forexample, to support many more wireless network devices, roaming wirelessnetwork devices and/or extended coverage regions, the access points onlyutilize wired backbone bandwidth if necessary. Each access pointattempts to minimize external bandwidth (of wired and wireless channels)by preferring internally performed relaying and, when needed,translation (between the first and second wireless protocols, or betweenthe wired protocol and either the first or the second wirelessprotocol).

The PBX system 1454 connects the wired backbone 1452 through a switchedtelephone network to other communication systems such as the system1452. This facilitates communications between all wireless and wirednetwork devices, such as the computer 1454, the device 1470 and remotenetwork devices (devices) connected elsewhere to the switched telephonenetwork. In circuit switched applications, a VLAN (virtual local areanetwork) can be established between wired and wireless network devicescoupled to the wired backbone 1452. Such coupling also includes remotenetwork devices coupled via the PBX system 1454.

FIG. 15 is a diagram illustrating the access point 1402 and portabledata terminals 1404 and 1406 of FIG. 14 a wherein a system 1500 routesvarious transmissions according to system conditions such as channelactivity, data type and data priority. In the system 1500, access point1402 forms cell 1512 while access point 1504, operating on only a singlechannel, forms cell 1514. Thus, while access point 1402 must determinehow to allocate wireless communications among the deterministic channeland non-deterministic channel in its cell 1512, access point 1504 routesall communications on its only channel.

In a first example of the operation of the system 1500, data fromcomputer system 1502 is transmitted to portable data terminal 1406. Thecomputer system 1502 transmits the data through the wired LAN backbone908 to the access point 1402. The access point 1402, having adeterministic transceiver 1412 and a non-deterministic transceiver 1414,routes the data through one of the transceivers. Based upon the type ofdata, the quantity of data, the rate at which data may be passed oneither channel, the amount of traffic on the channels and otherconditions, the control circuitry 1408 in the access point 1402 routesthe data on either the non-deterministic channel via thenon-deterministic transceiver 1414 or on the deterministic channel viathe deterministic transceiver 1412. In the present example, the data tobe transferred has a relatively low priority and the access point routesthe data on the deterministic channel to the portable data terminal1404. Likewise, print jobs from the computer 1402 to the printer 1510would also have relatively low priority and be transmitted via thenon-deterministic channel. Next, consider data transmissions fromscanner 1508 to computer system 1502. During operation, the scannertransmits an image to the computer system 1502 for decoding and thecomputer system 1502 returns decoded information at which point thescanner ceases scanning.

Rapid transmission between the scanner 1508 and the computer system 1502reduces the time within which the scanner 1508 performs scans. Thus,rapid transmissions may reduce energy consumption in the scanningprocess that drains battery life of the scanner 1508. Thus, the scanner1508 and access point 1402 both attempt to transmit data on thenon-deterministic channel at a relatively higher data transfer rate.However, if the non-deterministic channel is unavailable, thetransmission on the deterministic channel may be satisfactory.

In the case of a voice message transmission from portable data terminal1506 in cell 1514 to portable data terminal 1404 in cell 1512,transmission on the deterministic channel may be unsatisfactory. Thus,upon an incoming voice message transmission, the access point 1402 mayreallocate the deterministic channel allocating additional bandwidth forthe voice message. In an alternative operation, the access point 1402may interrupt communication on the non-deterministic channel andtransmit the voice message to the portable terminal unit 1404 on thenon-deterministic channel. Thus, in the mode of operation of the system1500 modifies its operation to provide sufficient bandwidth for thevoice message.

In view of the above detailed description of the present invention andassociated drawings, other modifications and variations will now becomeapparent to those skilled in the art. It should also be apparent thatsuch other modifications and variations may be effected withoutdeparting from the spirit and scope of the present invention as setforth in the claims that follow.

1-42. (canceled)
 43. Communication circuitry for communicativelycoupling a first roaming wireless device and a second roaming wirelessdevice, the communication circuitry comprising: a control circuit; awired transceiver that is communicatively coupled to the controlcircuit, the wired transceiver for coupling to the wired link; a firstwireless transceiver that is communicatively coupled to the controlcircuit, the first wireless transceiver for operating on a firstwireless communication channel to communicatively couple with the firstroaming wireless device; a second wireless transceiver that iscommunicatively coupled to the control circuit, the second wirelesstransceiver for operating on a second wireless communication channel tocommunicatively couple with the second roaming device; and the controlcircuit accommodates communications between the first wirelesstransceiver and the second wireless transceiver.
 44. The communicationcircuitry of claim 43, wherein the communication circuitry is adaptedfor coupling to computer interface circuitry.
 45. The communicationcircuitry of claim 43, wherein the communication circuitry is disposedon a module adapted for insertion into a computing device.
 46. Thecommunication circuitry of claim 43, further comprising a bus interfacecommunicatively coupling the control circuit to the first and secondwireless transceivers and the wired transceiver.
 47. The communicationcircuitry of claim 46, wherein the bus interface is substantiallycompliant with a bus standard.
 48. The communication circuitry of claim47, wherein the bus standard is a PCI standard.
 49. The communicationcircuitry of claim 43, wherein the wired transceiver accommodatescommunication with an Ethernet network.
 50. The communication circuitryof claim 43, wherein the wired transceiver accommodates communicationwith a token-ring network.
 51. The communication circuitry of claim 43,wherein the wired transceiver accommodates communication with anasynchronous transfer mode network.
 52. The communication circuitry ofclaim 43, wherein the wired transceiver accommodates communication witha packetized network.
 53. The communication circuitry of claim 43,wherein the first wireless transceiver supports a substantiallynon-deterministic media access protocol and the second wirelesstransceiver supports a substantially deterministic media accessprotocol.
 54. The communication circuitry of claim 43, wherein the firstwireless transceiver and the second wireless transceiver supportsubstantially distinct non-deterministic media access protocols.
 55. Thecommunication circuitry of claim 43, wherein the first wirelesstransceiver and the second wireless transceiver operate independently toform a first communication cell and a second communication cell.
 56. Thecommunication circuitry of claim 43, wherein the control circuitsynchronizes transmissions on the first wireless communication channeland the second wireless communication channel to minimize conflictsbetween transmissions on one wireless transceiver and receipts on theother wireless transceiver.
 57. The communication circuitry of claim 43,wherein the wired link is a local area network.
 58. The communicationcircuitry of claim 43, wherein the first wireless transceiver and thesecond wireless transceiver have substantially different operatingcharacteristics.
 59. Communication circuitry comprising: a firstwireless transceiver operating to establish a first wireless cell; asecond wireless transceiver operating to establish a second wirelesscell, the first and second wireless transceivers operating such that thefirst and second cells are substantially overlapping; a control circuitthat communicatively couples the first and second wireless transceiversto one another; and a wired transceiver that communicatively couples thecontrol circuit to a wired link, where the control circuitcommunicatively couples the first wireless transceiver and the wiredtransceiver.
 60. The communication circuitry of claim 59, wherein saidcommunication circuitry is adapted for coupling to computer interfacecircuitry.
 61. The communication circuitry of claim 59, wherein saidcommunication circuitry is disposed on a module adapted for insertioninto a computing device.
 62. The communication circuitry of claim 59,wherein the first and second wireless transceivers each compriseprocessing circuitry that supports a communication protocol.
 63. Thecommunication circuitry of claim 59, wherein the control circuit allowscommunications between the first wireless transceiver and the secondwireless transceiver.
 64. The communication circuitry of claim 59,wherein the first wireless transceiver supports a substantiallynon-deterministic media access protocol and the second wirelesstransceiver supports a substantially deterministic media accessprotocol.
 65. The communication circuitry of claim 59, wherein the firstwireless transceiver and the second wireless transceiver supportsubstantially distinct non-deterministic media access protocols. 66.Communication circuitry comprising: a control circuit operational to, atleast: communicatively couple to a wired transceiver operable tocommunicate over a wired link; communicatively couple to a firstwireless transceiver operable to communicate with at least a firstroaming wireless device over a first wireless communication channel;communicatively couple to a second wireless transceiver operable tocommunicate with at least a second roaming wireless device over a secondwireless communication channel; and accommodate communication betweenthe first wireless transceiver and the second wireless transceiver. 67.The communication circuitry of claim 66, wherein the control circuit isadapted for coupling to computer interface circuitry.
 68. Thecommunication circuitry of claim 66, wherein the control circuit isdisposed on a module adapted for insertion into a computing device. 69.The communication circuitry of claim 68, further comprising a businterface operational to communicatively couple the control circuit tothe first and second wireless transceivers and the wired transceiver.70. The communication circuitry of claim 69, wherein the bus interfaceis substantially compliant with a bus standard.
 71. The communicationcircuitry of claim 70, wherein the bus standard is a PCI standard. 72.The communication circuitry of claim 66, wherein the wired transceiveraccommodates communication with an Ethernet network.
 73. Thecommunication circuitry of claim 66, wherein the wired transceiveraccommodates communication with a token-ring network.
 74. Thecommunication circuitry of claim 66, wherein the wired transceiveraccommodates communication with an asynchronous transfer mode network.75. The communication circuitry of claim 66, wherein the wiredtransceiver accommodates communication with a packetized network. 76.The communication circuitry of claim 66, wherein the first wirelesstransceiver supports a substantially non-deterministic media accessprotocol, and the second wireless transceiver supports a substantiallydeterministic media access protocol.
 77. The communication circuitry ofclaim 66, wherein the first wireless transceiver and the second wirelesstransceiver support substantially distinct non-deterministic mediaaccess protocols.
 78. The communication circuitry of claim 66, whereinthe first wireless transceiver and the second wireless transceiveroperate independently to form a first communication cell and a secondcommunication cell.
 79. The communication circuitry of claim 66, whereinthe control circuit is further operational to synchronize transmissionson the first wireless communication channel and the second wirelesscommunication channel to minimize conflicts between transmissions on onewireless transceiver and receipts on the other wireless transceiver. 80.The communication circuitry of claim 66, wherein the wired link is alocal area network.
 81. The communication circuitry of claim 66, whereinthe first wireless transceiver and the second wireless transceiver havesubstantially different operating characteristics.
 82. Communicationcircuitry comprising: a control circuit operational to, at least:communicatively couple to a wired transceiver operable to communicateover a wired link; communicatively couple to a first wirelesstransceiver operable to establish a first wireless cell; communicativelycouple to a second wireless transceiver operable to establish a secondwireless cell that substantially overlaps the first wireless cell;communicatively couple the first wireless transceiver and the secondwireless transceiver to one another; and accommodate communicationbetween the first wireless transceiver and the wired transceiver. 83.The communication circuitry of claim 82, wherein the control circuit isadapted for coupling to computer interface circuitry.
 84. Thecommunication circuitry of claim 82, wherein the control circuit isdisposed on a module adapted for insertion into a computing device. 85.The communication circuitry of claim 82, wherein the first and secondwireless transceivers each comprise processing circuitry that supports acommunication protocol.
 86. The communication circuitry of claim 82,wherein the control circuit operates to allow communications between thefirst wireless transceiver and the second wireless transceiver.
 87. Thecommunication circuitry of claim 82, wherein the first wirelesstransceiver supports a substantially non-deterministic media accessprotocol, and the second wireless transceiver supports a substantiallydeterministic media access protocol.
 88. The communication circuitry ofclaim 82, wherein the first wireless transceiver and the second wirelesstransceiver support substantially distinct non-deterministic mediaaccess protocols.